Your question does not make a lot of sense. Con you better explain exactly what you are looking for?
The reason that I saw that is HTML is a scripting language for writing the structural layout of a web page. It has to do with page layout of the web pages.
WordPress of Joomla articles are normally written in plain text and copied into an administrative manager that displays that plain text content into a Word Press or Joomla web page. Very seldom will the plain text article file contain HTML scripting language. It can, but it normally does not as the administrator of the Word Press of Joomla site would not have HTML scripting knowledge. If they did they would normally not use that framework.
Could you better explain what you are looking for?